The University of Wisconsin Waisman Center on Mental Retardation and Human Development is engaged in biomedical and behavioral research. Biomedical research is carried out in two administrative sections, Neurochemistry and Neurophysiology. Within Neurochemistry, biochemical studies are being carried out on the roles in insulin and insulin-like peptides in the developing brain, the effects of deficient bilirubin metabolism on brain development, the effect of cell surface markers on neural development in the mouse trisome 16 (animal model for human trisome 21 (Downs Syndrome)), the characterization of antigenic markers on ganglion cells of the retina, and the elucidation of mechanisms underlying calcium function in the nervous system. Within the Neurophysiology Section, studies are conducted on the structure, function and development of the auditory, visual, and somatic sensory systems as well as on the hypothalamus. Anatomical studies are conducted on a resident macrophage system that resides in the brain ventricles. The cytoarchitectonic analysis of the monkey brain is being carried out in the construction of brain atlases. Six administrative sections are included in the Behavioral Research Unit. Perceptual and Neuromotor Processes Section investigators are concerned with perceptual and neuromotor processes, including visual mechanisms, neurophysiological processes of speech, their disorders and treatment, and measures of sensory function sensitive to pathologic events predictive of perceptual dysfunction. Those sections concerned with communication processes, audiology and Speech and Language Processes Sections, reflect a cluster of research interests related to the physiological, perceptual, psychoacoustical, cognitive, and linguistic processes involved in speaking and listening; their acquisition; their disorders; and their treatment. Infant Section investigators are involved in speech perception, caregiver-infant interaction, and attentional processes. Treatment Processes Section programs are concerned with psychological and social processes as applied to the solution of clinical or practical problems presented by the developmentally disabled and/or their families. Finally, the Psychophysics and Sensory Processes Section's programs are concerned with elucidating the development of sensory capabilities in non- compromised children and children with developmental disabilities, including those skills necessary for complex processes such as speech perception and mature communication skills.